Method of and apparatus for forming a refractory lining



D. L, SUMMEY July 23, 1935.

\ METHOD OF AND APPARATUS FOR FORMING A REFRACTORY LINING Original Filed April 14, 1932 3 Sheets-Sheet 1 v/ 8 m m w m m c U 6 ulmmwv H U C EM N N eX R L WME? 0 P w M m N V m m A a Mmu D h w on M y 23, 1935- I D. L, SUMMEY 2,008,732

METHOD OF AND APPARATUS FOR FORMING A REFRACTORY LINING Original Filed April 14, 1952 3 Sheets-Sheet 2 IHW o 0' N b? David L. summe deceased ll'lVENTOR The Colonial Irusi Company Richard P- W eks Surrimfy domr EXECUTQRS 5W fin 2i, wkibm 3 A ORNEYJT y 1935. D. L, SUMMEY 2,008,732

METHOD OF AND APPARATUS FOR FORMING A REFRACTORY LINING Original Filed April 14, 1932 5 Sheets-Sheet 3 David L. Summey deceased INVENTOR The Colon al 771151 Company Richard P- Weeks Somme,

Patented 7 July 23, 1935 METHOD OF AND APPARATUS FOR FORM- ING A REFRACTORY LINING David L. Summey, deceased, late of Waterbury, 001111., by the Colonial Trust Company, Watch bury, Conn., and Richard P. Weeks Summey, New York, N. Y., executors, assignors to Scovill Manufacturin g Company, Waterbury, Conn, a

corporation of Connecticut Original application April 14, 1932, Serial No.

805,147. Divided and this application Februmy 11, 1933, Serial No. 656,290. Renewed July 11 Claims. (CI. 13-30) This invention relates to a method of and apparatus for forming-a refractorylining for an induction heating unit and has for an object the provision of improvements in this art. This application is a division of the co-pending application of David L. Summey, Serial Number 605,147, filed April 14, 1932.

In transformer heating units for electric induction melting furnaces it is the usual practice to ram the lining into place about a core to form the channel which is to receive the molten metal secondary. For certain forms of channels the space to be filled with lining is often disposed behind the channel with reference to the point of application of the ramming tool. As a consequence, part of the lining may not be packed sufficiently so that it is soft and soon deteriorates. Again, the ramming may be done against a thin section of the furnace shell wall surrounding the core or lining form and this may cause the form orshell wall to vibrate, which will loosen adjacent lining material which has been previously packed, or will prevent packing it tightly enough to avoid seepage of metal from the channel into the lining after the furnace is put into service. Metal seepage of this character promotes and often causes early failure of the lining. When seepage occurs it has the effect of changing the cross section of the metal in the channel which alters the current. capacity of the electrical, circuit through the channel and causes local overheating of the furnace lining and furnace walls.

The ramming may warp or injure the shell or casing of the heating unit in such a way that the assembling of the unit after ramming is rendered difficult or impossible.

According to the present invention the ramming is done in such direction that no part of the channel stands in front of any other'part with reference to the point of entry of the ramming tool and the shell is brewed by a temporary structure during the ramming operation so that th shell will not be distorted. I In order to illustrate the principles of the invention it will be described in'connection with one type of heating unit and with one type of nent cover replaced by a temporary structure for the ramming operation; and

Fig. 4 is a view similar to Fig. 2 showing the method of ramming the lining.

A quicker understanding of the invention can be obtained by directing attention particularly to the specific type of heating unit shown in the drawings, though it must be remembered that this is not intended to impose any limits on the scope of the invention. In the heating unit shown, the secondary channel is V-shaped in a longitudinal plane through the channel legs, 1. e., in the channel plane, and each leg is rectangular in cross section. The lining for such channels has usually been introduced and rammed from the spread ends of the V and in adirection generally parallel to the central axis between the legs of the v. The result of this method of placing the lining was that the portions of the lining behind the channel have not been properly packed because they were inaccessible, the channel usually being relatively wide transversely of the channel plane. gFurthermore, ramming had to be done against the thin section of the channel form and this caused injury to the form or to the channel shape or to the lining. The central leg of the transformer passes through the unit between the legs of the V. A metal shell is used to enclose the core and the primary coil thereon and to retain the channel lining. The lining according to previous practice must be rammed behind, around'the sides of and in front of this shell. This prevented the proper ramming of a satisfactory lining because the ramming tool had to be directed broadside toward the shell. Also the shell was likely to be injured or distorted.

According to the present invention the lining is rammed in a direction parallel to the major cross sectional axis of the channel, 1. e., in lines perpendicular to the channel plane and the shell or casing of the heating unit is formed with a removable cover to permit such ramming. The ramming is thus conductedin a direction parallel to the wide section of the channel and parallel to the sides of the shell enclosing theprimary coil and transformer le'g therein, whereby vibration and injury to the lining are avoided. In additionto this, a skeleton frame i's-provided in place of the permanent cover to hold the shell sections 'in position to prevent distortion and permit easy fitting of the permanent cover after the lining has been placed.

Referring to the drawings, the heating unit is mounted upon the flange ill of the casing of a furnace hearth. The outer shell ll of the heating 2 7 unit is attached to the flange ill of the hearth casing by the bolts M. The shell II is formed in the shape of a deep box and is divided and insula'ted along the central axial plane-'22 perand the central transformer leg l8. The tubular ends of the legs of the V. The interior surface of the channel forms a complete circular loop about the transformer at its upper end but the outer surface extends tangentially from the short concentric arcuate portion starting approximately in an axial plane which is normal to the channel plane and to the axial plane 22. The-result of this formationis that a deep pocket 23 is produced at the upper-ends of the V.

In cross section the channel at any place therealong is rectangular, as shown in Fig. 2, with the major axis disposed normal to the channel plane.

The channel is formed by positioning a channel form in proper position in the casing and ramming the, refractory lining material about it. The form is composed of material that is easily destroyed by heat and is destroyed after the lining has been-placed. The lining is rammed by a tool 25, as shown in Fig. 4, the tool being introduced and acting in a direction perpendicular to the channel plane. This permits easy access to all parts of the lining and permits of the formation of a lining of substantially uniform character without soft spots and other defects.

During rammingthe casing is covered by a reticulated frame 26. This is the same shape. as the permanent cover and holds all parts of the frame in proper position so that when the permanent cover is applied it'will fit exactly. No parts of the casing can be sprung out of position or injured when this temporary frame is'employed. The openings in the temporary frame permit entry of the ramming tool at any point.

- During ramming the end of the unit which will be connected with the furnace shell may be covered with a solid plate 21 to retain the lining .material and form a smooth surface for the joint The core shell with the liningof the furnace. l6 herein is made relatively rigid but if it vibrates or springs during ramming it may be filled by a solid substance which can later be removed. In additionto the improved method of lining porary frame is replaced by the permanent cover,

V the channel form destroyed, and the transformerv core and primary coil are assembled on the eas- While oneembodiment of this invention has been described with particularity it is to be understood that the invention may be variously subjoined claims.

modified and embodied within the scope of the What is claimedis: Y

1. The method of ramming a lining for a secondary channel of an induction heating unit of a' metal melting furnace, in which the channel is enclosed within a lining disposed within a metal casing having a removable cover parallel to the channel, which method comprises providing a temporary grilled cover having the same outline shape and attaching elements as the permanent cover, attaching said grilled cover in place of the permanent cover and ramming the lining by tools passed through the openings of the grilled cover, for the purposes set forth.

2. In an electric induction furnace, an induction heating unit comprising a metal casing adapted to, receive a refractory lining enclosing a secondary loop channel, means on said casing forming a seat for a permanent cover, and a temporary grilled cover formed to fit in the place of the permanent cover and secured to the seat, the temporary cover serving to maintain the shape of the casing'during ramming of the lining and the grilled openings permitting the lin ing to be rammed through the cover.

3. In an electric induction furnace, an induction heating unit comprising a metal casing adapted to receive a refractory lining enclosing a secondary loop channel, means onsaid casing forming av seat for a, permanent cov'er parallel to the'plane of the loop channel, and a temporary grilled cover formed to fit in the place of the permanent cover and secured to the seat, the temporary cover serving to maintain the shape of the casing during ramming of thelining and the grilled openings permitting the lining to be rammed through the cover. v

' 4. The method of ramming a lining for a secondary channel of an induction heating unit'of a metal melting furnace in whichjthe channel is enclosed within a-lining disposed within a metal casing provided with a seat for a cover; which method comprises providing a temporary grilled 5. The method of ramming a lining for a secondary channel of an induction heating unit of a metal melting furnace in which the channel is enclosed within a refractory lining disposed within a metal casing having an open side for entry of lining material and aramming tool, which method comprises providing a reticulated bracing structurefor said opening and ramming the lining by a tool inserted through the openings of the structure. J

6. Inan electric induction furnace in combination, a box-like metal casing adapted to re-.-

ceiverammed lining material to define a loopshaped secondary channelparallel with the bottom of the casing, said casing being sufficiently deep to permit the lining material in substantial thickness to be placed on all sides of the channel and being provided with a seat for a cover approximately parallel with the plane of'the channel, a temporary cover fitting on said seat and having openings. therein for permitting linin material to be inserted and rammed in a direction normal to the plane of said channel, and means for securing said cover to the edges of said casing to hold it in shape while the lining material is being rammed.

'7, In an electric induction furnace in combination, a box-like metal casing adapted to receive rammed lining material to define a loopshaped secondary channel parallel with the bottom of the casing, said casing being sufllciently deep to permit the lining in substantial thickness to be placed on all sides .of the channel and being provided with a seat for a cover approximately parallel with the plane of the channel, a temporary form for defining said channel, a tubular metal member extending through said casing perpendicular to said loop, said member being adapted to receive a transformer core piece with a primary coil thereon, a temporary cover fitting on said seat and engaging the end of said tubular member, said cover having openings therethrough for permitting lining material to be inserted and rammed in a direction normal to the plane of said channel, and means for securing said cover to the casing seat and to the tubular member to hold the parts in position and shape while the lining material is being rammed.

8. The method of ramming the lining for a secondary channel ofan induction heating unit in a metal shell of relatively light material and having a metal core liner of relatively thin material, which comprises, securing the core liner at one end to the bottom of the shell while leaving the top open, placing a destructible channel form suitably disposed within the shell, placing a closure over the end of the shell which is to be attached to the furnace, placing a grid cover over the open top side of the shell, ramming the lining to form the channel and fill the shell, removing the grid cover and replacing it by a permanent cover, attaching the other end of the core liner to the permanent cover, removing the end closure, and thereafter destroying the channel form and attaching the shell to a furnace.

9. The method of ramming the lining for a secondary channel of an induction heating unit which comprises placing a grid cover over one side, ramming the lining through it and later substituting a permanent cover for the grid cover.

10. In a heating unit for an electric induction furnace comprising in combination, a shell open on one side to receive rammed lining material, and a temporary grid cover fitting over said open side to hold the shell in shape while the lining is being rammed.

11. Apparatus as set forth in claim 10 in which a secondary channel is formed in the lining material, said grid cover being provided with a grid bar in theshape of and disposed above the channel which is to be formed, and transverse grid bars holding said first grid bar in position.

THE COLONIAL TRUST COMPANY,

By EDWIN C. NORTHROP,

Vice President, RICHARD P. WEEKS SUMMEY, Joint Executors of David L. Summey, Deceased. 

